Murine models have been extensively utilized by Washington University Digestive Diseases Research Core Center investigators and are central to DDRCC biomedical research into inflammatory bowel disease and other aspects of the digestive system. The Murine Models Core has been and will continue to be dedicated to producing genetically altered animals and to providing gnotobiotic mice for DDRCC investigators in a timely and reliable manner. In addition, the Core provides ancillary sen/ices for maintaining mouse pedigrees, such as assisted reproduction and cryopreservation of embryos, as well as rapid transfer of mutations or transgenes from one genetic background to another using "speed congenics". We will continue to offer these services in the next project period.